ureadc(D3DK) —

NAME

ureadc − copy a character to space described by uio(D4DK) structure .IX \f4ureadc\fP(D3DK)

SYNOPSIS

#include <sys/uio.h>
int ureadc(int c, uio_t ∗uiop);

ARGUMENTS

cThe character to be copied.

uiopPointer to the uio structure.

DESCRIPTION

ureadc copies the character c into the space described by the uio structure pointed to by uiop.

The uio_segflg member of the uio structure specifies the type of space to which the copy is made. If uio_segflg is set to UIO_SYSSPACE the character is copied to a kernel address. If uio_segflg is set to UIO_USERSPACE the character is copied to a user address.

If the character is successfully copied, ureadc updates the appropriate members of the uio and iovec(D4DK) structures to reflect the copy (uio_offset and iov_base are incremented and uio_resid and iov_len are decremented).

RETURN VALUE

ureadc returns 0 on success or an error number on failure.

LEVEL

Base only if uio_segflg is set to UIO_USERSPACE. Base or interrupt if uio_segflg is set to UIO_SYSSPACE.

NOTES

May sleep if uio_segflg is set to UIO_USERSPACE.

Driver-defined basic locks and read/write locks may be held across calls to this function if uio_segflg is UIO_SYSSPACE but may not be held if uio_segflg is UIO_USERSPACE.

Driver-defined sleep locks may be held across calls to this function regardless of the value of uio_segflg.

When holding locks across calls to this function, drivers must be careful to avoid creating a deadlock. During the data transfer, page fault resolution might result in another I/O to the same device. For example, this could occur if the driver controls the disk drive used as the swap device.

Museum